Toll trunking circuits for machine-switching telephone systems



' R. L. STOKELY TOLL TRUNKING QIRCUITS FOR MACHINE SWITCHING TELEPHONE SYSTEMS Filed March 1, 1921 5 Sheets-Sheet 1 Apr. 17, .1923.

L. STOKELY TOLL TRUNKING CIRCUITS F OR MACHINE SWITCHING TELEPHONE SYSTEMS l/rvenfor Ray L Jib/rel E fihmzm my NQ SN @NN Apr. 17, 1923.

R. L. STOKELY T-OLL TRUNKING CIRCUI'IS FOR MACHINE SWITCHING TELEPHONE SYSTEMS Filed March 1; 1921 5 Sheets-Sh eet 5 Apr. 17, 1923.

v R. L. STOKELY -TOLL TRUNKING CIRCUITS FOR MACHINE SWITCHING. TELEPHONE SYSTEMS 5 Sheets-She d, 4

lnvenlbr. fay L. 5f0/re/y 1 h M my Apr. 17; 1923. J 1,452,323 R. L. STOKELY TOLL TRUNKTNG CIRCUITS FOR MACHINE SWITCHING TELEPHONE SYSTEMS Filed March 1, 1921 5 SheetsSheet 5 //Wenforfay L fiioke/y Patented Apr. 17, 1923.

units star any" L. STOKELY, or rnonnr. PARK, NEW roan, ASSIGNQR 'ro WESTERN nnnc'rnrc COMPANY, ncoeronnr-nn, or new YORK, N. Y., A CORPORATION or new YORK.

TOLL TRUNKING CIRCUITS F033, MACHINE-SVVITCHING TELEPHONE SYSTEMS.

Application filed March 1, 1921. Serial No. 448,890.

To all whom it may concern:

Bertknown; that I, RAY L. STOKELY, a

citizen. of the United States, residing at Flo-- ral Parlz, Long Island, in,the county of Nassau and State of; New York, have invented certain new and useful Improvements in Toll Trunking Circuits for Machine- Switching-Telephone Systems, of which the following. is a full, clear, concise, and exact. description.

This invention relates to machine switching telephone exchange systemswherein the substationlines are provided. with coin hoxes', andwherein it, is necessary to collector refund deposited coinsover toll switching trunks from atoll operators. position. It is an improvement uponthe system shown and described in my application for machine switching telephone exchange systems, Se rial No. 412.795. filed September 25, 1920. In

the systenndisclosedin that application, specialcoinicollect trunks must be provided from the toll position to the different automatic ofiices having coin lines, and thenumber of the particulartoll switching trunk usediby the toll operator in extending theconnection totheautomatic officeis dialed over oneof such special trunks; that is. to say, the toll operator afterhaving buil't up the connection over the conversational toll switching trunks. plugs into the jack of one of these special trunks leading to the distant automatic office through. which the connection to the calling line extends, this trunk terminating in special. connector? at such autoinaticofiice. The toll. operator by means. of the dial in her special cord circuit then sets such connector upon multiples of theused toll switching trunk in the automatic oiiice. She can then by means of collect and refund keys in such cord circuit impress current on the toll switching trunks and thence to the calling line to operate the polarized magnet in the coin bot: tocollect or refund the de posited coins.

In the present arrangement the relays at the automatic office which apply the coin current tot-lie-su'bstation line are operated'froin the toll position directly over the two-wire interoilice conversational toll switching trunk itself. thuseliminating the special coin collect trunks and the special connectors referred to, and also eliminating the extra dialing operation of the toll operator to set the: special connectors.

A further feature of this invention is-an arrangement for transmitting atone from the automatic office from which the currentfor operating the coin boxes is applied. back; to the toll operators head set to inform her that the coin collect or coin refund circuit, as the case may be, is functioning properly.

Referringto the drawings, Fig, 1 shows a toll cord circuit; Fig.- 2 shows a trunlr cir cuit outgoing from the tollboard to the full mechanical or automatic office; Fig. 3 shows an incoming selector thereat; Fig. 4 shows the relay and. repeating coil equipment associated with. the toll transmission selector. which selector is also shown on this sheet: Fig. 5 shows a combination toll and local connector circuit.

Referring first to Fig. 1, this. drawing shows a cord circuit at the toll operators position. Theleft-hand side of this circuit will be called the toll end and the righthand side will be called the toll and trunk end. In general, the operation, is as follows: The operator answers. an incoming call by inserting the plug T of the toll end in the answering jack-J. If the called subscriber is. located in a nearby automatic exchange, the call is completed. by inserting the plug T1" of the trunk and toll. endin a toll switching-trunk jack TSJ. The operatorthen actuates the dialing and monitoringkey DK which causes the relay 13-34 to operate, which in opcr ating energizes a monitoringiclay (not shown) to place the operators. telephone set 0. T. in a monitoring position on the cord. The operator now turns the dial D for the first digit ofthe'wanted number. '.I.he-clial in moving out of its normal position short circuits the relay B'-34.-. permitting the relay E-72 to operate. .ltlelay- E.72 in operating locks itself to battery and transfers the tip of the plug TT through the impulse springs 108 of the dial. D t o the battery. The dial. in returning to normal; interrupts the battery to the tip of the plugcausingthe impulse. relay A2 of: the trunk circuit of Fig. 5 to operate intermittently. the nuijnber of times; depending upon. the; digit involved. This impulse relay. in thus. operating. causes the setting of the incoming selector (Fig. at the distant automatic of fice which thereupon automatically finds an idle trunkin the selected level. This. trunk; includes the equipment shown Fig. 4;. and

terminates in the toll transmission selector shown in that figure. lVhen the operator has turned the dial for all of the digits involved causing the last switch or connector (Fig. 5) to be set on the desired line, she restores the monitoring DK. If the called line is not busy the trunk and toll supervisory lamp 100 lights as a ringing signal, whereupon the operator by depressing ringing key RK causes the connector to start the ringing of the called line, which ringing continues until the called party answers, whereupon the ringing current is cut oil and the lamp 100 is extinguished, When the called subscriber replaces his receiver, this lamp again lights as a disconnect signal.

If the called line is busy or if one of the selectors fails to find an idle trunk, the lamp 100 will flash, the frequency of the flashes depending upon the busy condition encountered. The toll operator in response to the flashing of the lamp removes the plug TT of the trunk and toll end of the cord from the toll switching jack TSJ, but before removing the toll plug T from ack J, the o ierator by means of her ringing key R l. rings on the toll line terminating at the jack J to notify the distant originating operator that the line is clear. If the distant originating operator rings first, however, the toll supervisory lamp 101 lights and when the operator actuates listening key LK, or pulls out the plug T this lamp is extinguished.

If the call is for a subscriber who can be i reached only over a toll line terminating at a toll position at a distant terminating oilice, the toll operator who answers the originating operator inserts the plug TT of the trunk and toll end in a toll line jack leading to such distant terminating oflice and by means of her ringing key RK rings out over such toll line to signal the distant terminating operator who then completes the connection. hen the terminating toll operator at the distant end applies ringing current to the trunk at the termination of the conversation, the toll supervisory lamp 101 lights until the listening key LK is operated or the connection is taken down. The keys K and K serve, when operated, to disconnect either end of the cord circuit from the operators telephone set when the operator is talking on the other end.

More in detail, when the plug T of the toll end is inserted in toll answering jack J. relay E-156 operates, in turn operating relay B162. Relay 13-162 opens the circuit of slow to operate relay E162 preventing the toll supervisory lamp 101 from lighting. When the plug TT or the trunk and toll end is inserted in toll switching trunk jack TSJ leading to an incoming selector at an automatic ofice, relay E99 operates in series with relay E155 and the right winding of relay E-156. Relay E-99 disconnects the busy test equipment of the operators telephone set from the tip of the cord and connects the tip of the cord through to the ring ing key. Relay 15-155 is marginal and does not operate at this time on account of the high resistance in the sleeve of the toll switching trunk circuit, and thus leaves the calling supervisory relay 13- 13 bridged across the trunk. Ringing current applied by a distant toll operator operates the alternating current relay A196 which releases relay B162. The latter relay in releasing lights the toll supervisory lam 3 101 and operates relay E-1G2 in parallel with the lamp. Relay E162 locks up under the control of the listening key LK and relay 1 1-156 so that the lamp remains lighted after the ringing ceases and the relay B162 is re-operated through the back contact of relay 21-196. The lamp 101 may be extinguished by operating the listening key LK which releases relay E162 or by taking down the connection which releases relays E-156 and E162. Relay E162 is made slow in operating to guard against the possibility of lamp 101 being lighted by Morse impulses. Relay A-196 may be operated for a short time by Morse impulses and release relay B162 momentarily, but the slow operating feature of the relay E162 will give relay B162 time to re-operate before the relay E162 operates and locks. When the plug TT of the cord is contemporaneously inserted in a toll line jack similar to jack J terminating at another toll board position, the marginal relay E155 disconnects the calling supervisory relay B-43 from the cord'circuit. It, on a through toll connection of this character the splitting key K is operated to disconnect the trunk and toll end TT from the operators telephone set, relay B-43 is bridged across the trunk and toll end so that it will operate when ringing current is received 'from the toll board position in which he toll line associated with the trunk and toll end terminates and flash the lamp 100. Since the splitting key K is actuated, relay i l-196 is not operated by such current.

When the splitting key K is in its normal position this bridge for relay B43 is opened.

Referring now to Fig. 2 which represents a toll switching trunk over which a connecticn is extended to an automatic exchange, rela C 4? operates over its right-hand wind ing when the opera tor inserts the plug TT into jack TSJ and by attracting its armature closes a loop circuit leading to the impulse relay i l-3 of the incoming selector Fig. 3 at such exchange. When the dialing key DK is thrown and the dial is operated, relay A-2 operates. connecting relay I2 across the loop leading to the impulse relay $i-3 of the incoming selector at the automatic office, Fig. 3. Relay I2 in operating causes slow relay D-2 to operate, which relay shunts the left-hand winding of relay C2 whereupon the latter relay releases, the circuit through its right-hand winding being opened when relay E72, Fig. 1,

operates as the dial is moved out of its nor-' mal position. Relay D2 in operating op erates relay E2 which locks up to the ground at the inner left contact of relay B2, now energized. Relay E2 at its outer leftcontact locks relay D2, independently of its original energizing circuit which leads over the front cont-act of relay I 2. The dial, in restoring, intermittently operates relays A-2 and I2, relay A2 intermittently opening the loop circuit to the impulse relay A-3 of the incoming selector and relay I2 alternately opening and closing a shunt path around relay D2. If, during the operation of building up a connection, one of the selectors fails to find an idle trunk in the selected group, it opens the loop circuit including relay I2. Belay I-2 in closing its back contact perm-anently shunts out relay D2. Relay D2 in closing its right-hand contact operates relay H2. Relay H2 locks up and connects interrupted battery of impulses per minute to the winding of relay Cz in shuntof the" resistance 200. Relay B41:3 in the cord (Fig. 1) follows these impulses and flashes the supervisory lamp 100 to indicate to the operator the failure to find an idle trunk. y y

In case the called line is busy, interrupter 233 is connected in circuit to flash the lamp 100 at a different rate to indicate to the operator the busy condition of the selected line.

In case the called'subsrribers line is found to be idle by the connector (Fig. 5) this condition causes the polarized relay F 2 to operate and cause lamp 100 to remain steadily lighted as a ringing signal when the operator restores the key LK. Relay F2 in operating also energizes relay G-2 which cutsthe trunk through, thus disconnecting the relays C2 and A2 from the circuit leading back to the toll operators position. Having described in a general manner the operation of the system, a call will now be traced in detail.

The toll operator, having been informed of the number of the wanted linejand assuming this line to be in a nearby automatic exchange. tests for an idle trunk by touching the tip of her plug TT to the sleeve" of the jack TSJ of the toll switching trunk, and if she does not receive a click in her receiver she inserts the plug. TT into the toll switching trunk jack TSJ.- A. circuit is thereupon closed to operate relays E-99. (Fig.1) and B2 (Fig.2), RelayE99 in operating disconnects the, operators busyte'st circuit from the tip of the cord. Relay B2 (Fig. 2) in operating prepares certain circuits which will be traced later. This trunk will now test busy at the other operators positions due to battery applied to the sleeve multiples by the sleeve of the plug TT. The insertion of the plug also closes the following circuit to energize relay C 2; free pole of battery, resistance 200, right-hand winding of relay (3-2, conductor 201, armature 202 of relay G2, conductor 203, ring of the jack TSJ, ringof the plug TT, normal contact of keys 181 and BK, right-hand winding of retardation coil 120 relay B.43, armature and back contact of relay E-155, which relay is not operated when the plug TT is inserted in the toll trunk switching jack leading to an automatic ofiice but only when it is inserted in a toll line leading to a position at a distant oflice, left-hand winding of retardation coil 120, upper normal contact of ringing key R-K, armature and front contact of relay E99, contact of. key 180, conductor 121, right-hand normal contact of relay Pl -72. conductor 103, tip of the plug TT, tip of the ack TSJ, armature 204 and back contact of relay G-2, and relay A-2 to ground. Relay A2 is marginal and does not operate in this circuit. Relay (7-2 in attracting its armature closes the following circuit to operate relay A- 3, Fig. 3, which is the impulse relay of the incoming selector at the automatic oflice shown in Fig. 3: free pole of battery. left winding of relay A-3 (Fig. 3),.conductor 300, back contact and armature 301 of relay D--3. conductor 302. conductor 203, conductor 206. outer left-hand armature and back contact of relay H2,conductor 207, armature and front contact of relay 0-2, left-hand winding of relay C--2, conductors 208 and 209. inner right armature and front contact of relay 13-2, conductor 210'. polarized relay F2, conductor 211. conductor 2'12, conductor 303,

armature 304C and back contactof relay D-3,

conductor 305, right winding of relay A--3. conductor 306. normally closed contact of switch 307, operated on the eleventh rotary step of the selector. to ground. The operator now throws the dialing and monitoring key DK, whereupon a circuit is closed to operate relay B34, Fig. 1. which in attracting its armature causes the operators head set to be connected. across the cord. She now rotates the dial D for the first di it of the wanted number. The closure of the contact 104 of the dial as the dial moves oif normal. shunts the relay B'34c which shunt operates the relay E72' and releases relav B3 l. Relay E-72 in attracting its lefthand armature locks itself to ground at the contact of the dialing key DK which when ectnated remains in its operated position until manually released by the operator.

215, relay D Relay E72 in closing its right-hand contact connects free pole of battery through the impulse contact 108 of the dial. to the tip of the plug interposing a break in the tip conductor. The interposition of this break in the tip conductor opens the circuit heretofore traced through the right-hand winding of relay C- Marginal relay A.2 now operates in series with the impulse contact of the dial, the circuit being as follows: free pole of battery, resistance 109, impulse contact 108, righthand armature and front contact of relay E-j72, conductor 103, tip of the plug TT. tip of. the jack TSJ. armature 204 and back contact of relay G-2, conductor 213 and relay r r2 to ground. Relay A2 in attractingits left-hand armature bridges relay I2 across the tip and ring of the trunk in parallel with the left-hand winding; of relay C2. Relay I2 in attracting its armature closes a circuit, to operate slow relay as follows: free pole of battery, resistance 214;, conductor 2, conductor 216, right armature and front contact of relay lI2, conductor 217. contact 218 of relay G to ground. Relay D 2 in attracting its left armature short circuits the left-hand winding of relay C-2 which thereupon releases. thus opening one of the bridsres to the impulse relay A-3 and leaving bridged across the circuit only relay l2. This circuit may be traced as follows: free pole of battery. left winding of relay A 3, conductor 300, armature 301 and back contact of relay D-3, conductor 302, conductors 203 and 206. outer left-hand armature and back contact of relay H2, conductor 207. conductor 208. relay'I2, left-hand armature and front contact of relay A 2. conductor 211. conductor 212. conductor 303, armature 304 and back contact of relay D3. conductor 305. right winding of relay A.3 and upper normal contacts of switch 307 tog'round. Relay D-2 at its right armature and front contact closes the following circuit to operate relay il-2: free pole of battery, relay E-'-2. conductor 220. right armature and front contact of relay D 2. conductor 221. conductors 282 and, 228. inner left armature and front contact of relay B2 to ground. vRelay ll2 in attracting; its inner right armature locks itself to arounded conductor 282. The func tions of his relay will be later described. Dial D. Fig. 1. in returning to normal. in terrupts at its impulse contact 108 the cir cuit of the impulse relay- A 2. Fig. which at its left armature interrupts the circuit of the impulse relay A. 3. Fig. 3, the number of times corresponding to the first digit of the wanted number. Upon each retraction of the armature of relay the following circuit is closed or the vertical inaa'net 310 of the first selector: grounded armature 311, and back contact of relay D-3, conductor 312, armature and back contact of relay, A 3, right armature and front contact of slow relay B3, slow relay C3,. vertical magnet 310, and free pole of battery. Relay B3 operated when relay A 3 operated. 0n the first step of the selector oft normal springs 313 close the following circuit for relay 314; free pole of battery, relay 31 1-, conductor 315, off normal springs 313, conductors 316, 317, armature and front contact of relay C-3 to ground at the left arn'iature and front contact of relay B-3. Belay 31 1 in attracting its right armature locks over the following circuit: free pole of battery, relay 314, conductor 315. off-normal contact- 313, conductor 316. armature and back contact of rotary magnet 318. conductor 319, conductor 320, right armature and front contact of relay 314i, conductor 321 to ground at the armature 311 a-ndback contact of relay D3. Upon the cessation of the impulses, however. relay A3 remains energized and consequently relay C-3 which is slow to release, after an interval, releases whereupon the following circuit is closed to energize the rotary magnet 318 of the selector to step the selector brushes on to the first trunk in the selected level: free pole of battery, magnet 318, conductor 322, left armature and front contact of relay 314, normal contact of relay C3, left armature and front contact of relay B-3 to ground. At the end of its stroke, the rotary magnet 318 opens the locking circuit traced for relay 314. Relay 314 in retracting its left armature opens the circuit of the rotary magnet. If the first trunk is busy, ground is present on the test multiple thereof. whereby the following circuit is closed to again energize relay 314; grounded multiple 323. test brush 324, conductor 325. armature 326 and back contact of relay D-3, conductors 327, 319. back contact and armature of magnet 318. conductor 316. contact 313, conductor 315. relay 314 to free pole of battery. Relay 314 in attracting its right armature again locks itself throusrh the hack contact of the rotary magnet and in attract-- inc: its left armature again closes the circuit of the rotary inan'net whereupon the selector brushes are stepped to the next trunk. This interaction of the relay 314 and rotary magnet is continued until an idle trunk is found which indicated by the absence of around on the test multiple 323 thereof. When the rotary magnet at the end of its stroke posit ons the brushes. on an idle trunk relay 314- does not energize but relay D3 energizes over the following circuit: free pole of battery, relay 314, conductor 3155. contact 313. conductor 316. armature and back contact of rotary magnet 31.8. conducto 319. conductor 327. conductor 328, relay D-3, conductor 329, lower normal contact of switch 307, conductor 330, to ground at the left armature and front contact of relay B3. Relay 314 is marginal and does not operate in this circuit. Relay D3 in attracting its armatures 304 and 801 extends the talking conductors through to the selector brushes and cuts off impulse relay A*3.

Assume now that the selector has failed to find an idle trunk. In that event on the eleventh rotary step, switch 307 operates and opensthe circuit of the impulse relay A 3 which causes the selector (Fig. to restore. The opening of this loop circuit also causes relay I2 to be permanently deenergized. hen the operator transmits all of the digits relay A2 remaining attracted and the relay I2 being inert, the following short circuit is closed about the slow relay D2 to cause the same to release: free pole of battery, resistance 214, right-hand armature and front contact of relay A-2, armature and back contact of relay I2, conductor 217, contact 218, to ground. It will be understood that relay D2 is slow to release as shown and holds up between the impulses. Relay D2 in retracting its right armature operates relay H-2 over the following circuit: free pole of battery, relay H2, conductor 222,111111 ture and back contact of relay D--2, conduct-or 220, inner right-hand armature and front contact of relay E'2 to ground on conductor 282. Relav E+2 in attracting its inner left armature locks itself to grounded conductor 282 and in attracting its inner right armature connects interrupter 223 to shunt the resistance 200 to cause superyisory relay B-43 in the cord circuit to flash the trunk and toll supervisory lamp 100 at the rate of 60 flashes per minute .when the operator restores the key DK. This rate of flashing will indicate to the operator that one of the switches has encountered a busy trunk group whereupon she will remove the plug and will then wait and set up the connection later. While the interrupting machine 223 is connected to the front contact of relay H 2 as soon as relay D2 releases, this operation is not effective to flash the lamp until the operator, after having turned the dial for the last time, releases her dialing key DK, Fig. 1. The opening of the lowermost contact of this key releases relay E-72 which in retracting its right armature again closes the loop circuit including the right-hand winding of relay C2, Fig. 2. and the relay A2,1Fig. 2 and Beet? F 1). The.

relay H'2 in attracting its outer left arma ture interposes a break in the loop circuit leading to the selector (F 3) thus preventing the subsequent sets of impulses from being transmitted.

The seizure of the toll transmission selector, Fig. 4, causes the closure of the following circuit for impulse relay ()4, Fig. 4 of the toll transmission selectors; free pole of battery, left-hand winding of relay O4, conductor 400, inner right armature and back contact of relay F4, conductor 402,

normal contact of relay B-4, lower left ing of the repeating coil, conductor 406,

contactof relay B4, conductors 407, 408, contact 453 of relay F-4, conductor 400 through the right winding of relay 0-4 to ground at the lower normal contact of the switch Y4 which is operated on the eleventh rotary step of the transmission selector. The impulse relay 0-4 in attracting its right armature energizes slow relay Q.-4. This relay in attracting its inner left armature applies a ground over the sleeve wire 410 to multiple 323 to cause this trunk to test'busy and to hold up the release relay D-3 of the incoming selector in the well-known manner. lVhen the re lay Q-4 operates it clo'sesat its outer lefthand armature the following circuit for relay J'4 in the relay and repeating coil circuit; ground, outer left armature and front contact of relay Q,4, conductors 403 and 411, contact 412 of relay -M-4, conductor 418, outer right-hand armature and back contact of relay B'4, relay J-4 to free pole of battery.

The second operation of the dial by the operator transmits the second digit of the called line causing relay A2 Fig. 2 to open and close the loop circuit for the relay O 4, which in vibrating its right-hand armature transmits impulses over the following circuit to the vertical magnet V'4 of the toll transmission selectors, grounded right arma ture and back contact of relay O4, inner armature and front contact of relay B-'4, inner armature and front contact of'relay Q-4, conductor 414, armature 415 and back contact of relay M-4, slow relay T4, magnet V'4 to free pole of battery. The brushes of the toll transmission selector are thus elevated to the desired level. WVhen the dial returns tp normal and maintains the relay A-2 energized, relay Q-4 remains energized and, after a slight interval, slow relay T 4 releases. \Vhen the relay T 4 operated on the first impulse and the selector took its first step, relay S4 operated over the following circuit: free pole of battery,

relay S4, upper contact of off normal switch 416, armature and front cont-act of relay T4, conductor 418, to ground at the left armature and back contact of relay 1 -4. In attracting its inner armature, relay S4 locks itself to its own inner left armature and front contact, this circuit including the armature and back contact of rotary magnet R-4. Upon the cessation of the impulses and the release of the slow relay T-4, the circuit of the rotary magnet is closed as follows: free pole of battery, magnet R-4, outer left armature and front contact of relay S4, normal contact of relay T-4, conductor 418, left armature and back contact of slow relay 1 -4 to ground. The rotary magnet advances the brushes onto the terminals of the first trunk and at the end of its stroke opensthe locking circuit of the relay S4 which releases, opening the circuit of the rotary magnet. If the trunk is busy, relay S-4 again energizes over the following circuit: free pole of battery, relay S4, upper contact of switch 416, conductor 419, armature and back contact of rotary magnet B4, conductor 421,

back contact and armature 422 of relay M--4, conductor 423, armature and back contact of relay P4, conductor 424, test brush 425 to ground on the test multiple 426. Relay S-4, in attracting its inner armature again locks and again closes the circuit of the rotary magnet which advances the brushes to the next trunk and at the end of its stroke opens the locking circuit of relay S-4 which in retracting its armature opens the circuit of the rotary magnet R4. The switch -4 of the toll transmission selector, Fig. 4, corresponds to the switch 307 of the selector circuit, Fig. 3. Its function is to open the circuit of the impulse relay O4 in the eleventh rotary step of the toll transmission selector, that is to say, if all the trunks in the group are busy. The opening of this circuit releases the switch and causes relay I-2 Fig. 2 to become permanently inert which causes the release of slow relay D-2 and prepares a circuit for the interrupter 223 which results in the flashing of the trunk and toll supervisory lamp 100 when the operator restores her dialing key as described in detail in connection with Fig. 3.

If, however, an idle trunk is found by the selector (Fig. 4) relay M4 operates over the following circuit: free pole of battery, relay S4, upper contact of switch 416, conductor 419, armature and back contact of magnet 11-4, conductors 420, 421. relay M-4, upper normal contact of switch Y-4, conductor 403 to ground at the outer left armature and front contact of relay Q-4. Relay S4 is marginal and does not operate in this circuit in series with the relay M-4. Relay M4 in attracting its armatures 427 and 428 extends the talking conductors through to the talking brushes 429 and 430. The attraction of the armature 422 of relay M4 grounds the test brush 425 and consequently test multiple 426 of the selected trunk, causing the same to test busy to other selectors. The contact 431 is made before the contact 412 is broken by the armature 432 of the relay M-4. Consequently relay J4 Fig. 4 in the relay and repeating coil-equipment is maintained energized over the following circuit: free pole of battery, relay J4, outer right armature and back contact of relay B-4, conductor 413, contact 431, brush 433, multiple 434, control conductor 435, conductor 500, conductor 501, armature 502 and back contact of relay K-5, conductor 503, sleeve conductor 550, conductor 436, multiple 426, brush conductor 424, outer right armature and back contact of relay P-4, conductor 423, armature 422 and front contact of relay M-4, conductor 403, to ground at the outer left armature and front contact of slow relay Q 4. Thus, the circuit for relay J-4 (Fig. 4) is maintained closed as the circuit is extended from switch to switch. As will hereafter appear, relay B4 is not operated until the desired line is found idle and seized, when it reverses the direction of current flow in the circuit leading back to the toll operators position to light the supervisory lamp 100 to indicate to her the idle condition of the line, whereupon she will cause the connector to begin the ringing operation. The switch of Fig. 5 to which the connection has been extended is a combination toll and local connector containing multiples of ordinary lines in its bank. only to the toll transmission-selectors of Fig. 4, but also to the local selectors which are used by the subscribers in building up their own local connections. The seizure of the connector causes the closing of the following circuit for the impulse relay A.5: free pole of battery, upper winding of relay A-5, conductor 504, conductor 505, left winding of slow relay J5, conductors 506 and 507, lowermost armature and back contact of relay K5, ring conductor 546, conductor 437, multiple 438, brush 430, conductor 439, armature 428 and front contact of relay M4, left armature and front contact of relay 0-4, lower armatures and back contacts of relays L4 and K4, lower right-hand winding of the repeating coil 404, resistance 440, inner left armature and front contact of relay J4, resistance 441, resistance 442, upper right hand winding of repeating coil 404, upper armatures and back contacts of relays K4 and L4, armature 427, and front contact of relay M-4. brush 429,1nultiple 442, tip conductor 443, conductor 510, upper armature and back This switch is accessible not itself as follows: free pole of battery, right winding and right innermost armature and front contact of J5-, conductor 514, conductor 531, conductor 515 to ground at the armature 516, and front contact of slow relay B-5 which is energized upon the energization of the impulse relay A-5. Relay B5 grounds the sleeve wire 517, leading to the test multiples in the local selectors, this circuit leading from grounded armature 516, conductor 515, to conductor 517. The return of the dial to normal in the operation of transmitting the tens digit of the wanted number interrupts the circuit of relay A2, F ig.- 2which in turn interrupts the circuit of the impulse relay A-5, Fig. 5 which in vibrating its armaturcs transmits impulses to the vertical magnet 518 of the connector over the following circuit: free pole of battery, magnet 518,

slow relay 519, right contact of off normal switch 520, conductor 521, lower armature and front contact of relay B-5 to ground at the armature and back contact of the impulse relay A5. At the first step of the connector, the off normal springs 520 are shifted and the succeeding impulses are transmitted by Way of the upper armature and front contact of relay 519 and the contact 522 now closed at the off normal springs 520. The connector brushes are thus lifted to the desired level and upon the cessation of the impulses, impulse relay A5 remains energized and relay 519 in series with the vertical magnet releases preparing the circuit of the rotary magnet 523. The units impulses pass through the back contact of the impulse relay A5, lower armature and front contact of relay B5, conductor 521, off normal contact 522, back contact of slow relay 519, conductor 524, left armature and back contact of relay G5, conductor 525, uppermost armature and back contact of relay H5, rotary magnet 523 to free pole of battery. The connector is thus stepped around into engagement with the desired line.

If this line is idle, full potential is present on its test multiple 526 through the cut off winding of the line switch and the following circuit is closed to operatefi'relay H.5; multiple 526, brush 527, conductor 528, right-hand armature and back contactof relay E5, conductor 529, upper winding of relay H5, conductor 530, right-hand armature and back contactof relay (Jr-53, conductor 531, conductor armature 516 of relay B5 to ground. Relay H-5 in attracting its armature 532 locks itself to the grounded sleeve wire 550 and extends this grounded wire 550 over conductor middle right armature and front contact of relay J5, conductor 53% to the relay K-5. Relay K5 in attracting its armature 502 disconnects the grounded sleeve wire 550 from the control lead 500 leading back to the relay J-4, Fig. 4: of the relay and repeating coil equipment circuit. Relay J1 in retracting its outer left-hand armature operates relay Fig. 4: over the following circuit: free pole of battery, relay B-, outer left armature and back contact of relay J- l, conductor 34 1. armature 422 and front contact of relay M-4, conductor 403 to ground at the outer left armature and front contact of relay Q,f. Relay B-i in attracting its outer right armature closes a substitute ground to hold up the slow relay F5 to prevent ringing from occurring at this time ground, left-hand arimiture of relay E4c, conductor 315, outer left armature and back contact of relay F4t, outer right armature and front contact of relay 3Z I, control conductor 113., contact 131 of relay Mf, brush 133, multiple 413-1, conductor 135, conductor 500, front contact and armature and lower winding of relay F-5 to free pole of battery. Relay F-5 was energized upon the first impulse to the vertical magnet, this circuit being as follows: free pole of battery, lower winding of relay F-5, lower armature and front contact of slow relay 519, innermost right-hand armature and front contact of relay J 5, conductor 514:, conductors 531 and 515 to ground at the upper inner arn'iature and front contact of relay B5. \Vhen energized, relay F-5 is locked by way of its armature 535 and front contact, conductor 501, armature 502 and back contact of relay K5 to grounded sleeve wire 550. Consequently, the operation of relay l --5 to cause the reversal of direction of the current flow in the loop leading back to the toll o-perators position opened the circuit of slow relay F-5 and unless a sub stitute circuit is provided for holding it up the ringing operation would automatically take place. This is prevented by applying a substitute ground. to the control conductor 500 as described over the circuit traced to hold the relay F5 until the operator, by depressing a key as will be explained, releases it to start the automatic ringing operation. The release of the relay J4c and the consequent energization of relay 3-4 as described reverses the direction of current flow in the talking conductors leading back to th operators position. After having turned the dial for the last digit the o )erator restores lay A2. Relay A-2 it will be remembered, releases under this condition and in retracting its left armature deenergizes relay I-E.3, which in releasing causes the release of relay l)-2. The polarized relay F 2 is now bridged across the trunk from upper talking conductor 212, Fig. 2, conductor 211, polarized relay F2, conductor 210, inner right armature and front contact of relay ll-2, conductor 209, conductor S, left-hand winding of relay (e- 2, armature and front contact of relay C2, conductor 207, outer left armature and back contact of relay Til-42, conductor 206 to lower talking, conductor 203. The reversal of the direction of current in the talking conductors due to the operation of relay Bl causes the relay F-2 to operate closing the following circuit for relay G2: free pole of battery, relay (E 2, conductor 22a, contact 22:) of relay l 2, conductors 226, 227, 228. inner left armature and front contact of relay B--2 to around. Relay G-2 locks itself up over the following circuit: free pole of battery, relay (l-2, conductor 224, conductor 229. front contact and armature 230 of relay G2, conductor 231, conductors 227, 228 to ground at the inner left-hand armature of relay l3-2. Relay 2 connects the talking conductors of Fig. 2 through to the talking conductors of Fig. l whereupon the trunk and toll supervising relay B- l3 operates in series with the relay A-5 Fig. 5 and lights the supervisory lamp 100 as a ringing signal to the toll operator. Relay G-2 Fig. 2 cuts off the bridge including relays C2 and A-2. It will be noted that when relay D-2 releases, relay H2 operates over a circuit traceable from free pole of battery, relay H2, right-hand armature and back contact of relay D2, inner right-hand armature and front contact of relay E-2, conductors 282 and 228 and the inner left-hand armature and front contact of relay B-2 to ground. The left-hand armature of relay H 2 in opening its back contact, interrupts the bridge including relay F2 and the left-- hand winding of relay C-2. However, due to the operation of relay G 2., the toll supervisory lamp will not flash. Relay C-2, in rs-ileasing. introduces,another break in the bridge previously traced for polarized relay F2. The operator now operates her ringing key R-K which impresses alternating current upon the talking conductors to operate the alternating current relay ilkl in bridge of the trunk (Fig. 4) which in attracting its armature operates the relay E l. This relay in attracting its right armature opens the circuit heretofore traced, which has been holding relay F--5, Fig. 5, energized. This relay in retracting its armatures 536, 53?, connects ringing" current to the called line through its upper winding. This ringing current is continued until the called party removes his receiver, resulting in an increase in the current through the upper winding of relay l -5 causing the same to operate removing: the ringing current. The attraction of the armature of this relay closes a locking circuit for the same over control conductor. 500 as traced to ground at the back contact of E l. The extension of the tip and ring conductors by relay F-5 to the called line operates relay GZl over the windings of which talkingcurrent is fed to the called line. Relay 1- l in operating energizes relay F-a which in attracting its outer left-hand armature applies ground to the control conductor 413 to hold up relay F-S, F 5 independently of the relay E '-l. Relay F4l in attracting its inner left armature closes a bridge across conductors M6, 409, to hold up relay O-L and opens the connection of battery through the windings of relay O lto the talking conductors leading back to the operators position which causes the deenergization of supervisory relay B- lil. This relay in retracting its armature extinguishes the supervi ory lamp 100 which notifies the operator that the subscriber has responded. Talking cur rent is fed to the called line over the windings of relay Gal and the repeating coil 404. This talking circuit is a standard repeating coil transmission circuit used in long distance connections. Talking current is fed to the calling line from the distant exchange. During conversation the trunk leading; from the left-hand windings of repeating coil 40% through the right-hand windings of the repeating coil (not shown) at the distant office is dry, in accordance with standard practice.

The operator now operates her listening key LK and requests the original calling now the called subscriber at the substation shown in Fig. 5 to deposit the necessary coins in, the coin box which may be of the type shown in Patent 1,043,219. issued November 5, 1912, to O. F. Forsberg. These coins in passing through the box strike gongs whereby the operator is informed of the denominations of the coins inserted. lVhen she is satisfied that the proper coins have been deposited she presses the collect key 181 which operates relay C-l thereby applying positive current from the relatively high potential source 447 at the automatic oflice to the subscribers line to operate the polarized magnet P in the coin box to collect the deposited coins. The circuit for operating relay Cl is as follows: free pole of battery 130, key 181, rings of the plug and jack, lower or ring conductors Figs. 2 3 and 4:, lower left-hand winding of repeating coil lOl, inner right armature and front contact of relay B4-, left armature and back contact of Dl, relay Cel,

conductor e08, to ground at the outer right armature and front contact of relay F4. Relay C-4 in attracting its innerleft armature operates relay K4 which connects the outgoing tip and ring conductors to conductor 448 leading to the source of positive charging current 447. This current flows out over the talking conductors in parallel to ground through the polarized magnet P in the coin box which operates to collect the coins. The relay H4 operates in this circuit and at its outer right armature and the right armature of relay C4 applies a distinctive tone from a source 451 to the tip cdnductor and thence to the operators head set. This circuitincludes the upper or tip conductor Figs. 4, 3, 2 and 1, right normal contact of relay E72 normal contact of key 180, alternate contact of key l d-99., normal contact of keys BK, K, alternate contact of listening key LK, the operators head set,

alternate contact of key LK normal contacts of keys K, RK to ground at alternate contact of key 181. This tone informs her that the coin circuit is functioning properly. When she releases the collect key the relay C4 releases, disconnecting the charging current from the line whereupon the polarized magnet restores and opens the contact 538 disconnecting the magnet from the line. She now again presses the key and if the coin box magnet has functioned properly and thus removed the ground, the relay I-L-4 will fail to operate and she will not hear the collect tone in her head set. If, on the other hand, it has not operated the ground remains connected and the relay H-4 again causes a tone tobe transmitted to her head set. If she cannot by repeated closures of the key 181 disconnect the tone she knows the coin box is defective and reports the line out of order.

Assuming however that the coins are collected she restores her listening key LK and allows the conversation to proceed.

If the subscriber at station A desires the attention of the operator he moveshis switch hook up and down which causes the supervisory lamp 100 at the operators position to flash, as in usual manual practice, without releasing'the switches. This is apparent from the preceding description inasmuch as relay G-4, Fig. 4 is in circuit with the called line and each time it retracts its armature it removes battery and ground from the trunk conductors leading back to the supervisory relay 13-43 and puts a bridge including resistance 401 across the relay O4 to hold it operated.

If for any reason the deposited coins are to be refunded the operator actuates refund key 180 which operates relay D-4 which .applies current of negative polarity from the source 452 at the automatic oflice to the line to operate the coin box magnet in the other direction to refund the coins. The cirductor 448 to which is now connected nega-' tive current at the outer right armature of relay D4 from source 452. The coin box magnet operates in this circuit to refund the coins and relay H-4 cooperates with relay D.% to connect tone of a different character from source 450 to the ring conductor and thence to the operators head set to inform her that the coin circuit is functioning properly. When she releases key 180 and again depresses it she will hear no tone if the coin box magnet P has operated and removed the ground, and if it has not she will again receive the tone as in the former case.

The replacement of the receiver by the subscriber does not remove the control of the coins from the operator. If she depresses the collect key after the subscriber has re placed his receiver the circuit for relay C4 leads to ground through contact 453 of relay F4, conductor 409, and the right coil of relay O-4 instead of at the outer right armature of relay F+4. This relay releases when relay Gr-4 in the line circuit releases due to the replacement of the receiver. If the refund key is operated under these circumstances the relay D 4 is operated through the battery connected to the left coil of relay O4.

When the called subscriber replaces his receiver the lamp 100 at the toll operators position Fig. 1 is lighted. The operator may re-ring the subscriber, if she desires to recall him, by actuating her ringing key RK which operates relay A4 to operate E4 which in attracting its left-hand armature again releases relay F--5 Fig. 5 which initiates the ringing operation. this relay F5 was removed from the relay E-4 by the attraction of the outer left armature of relay F4 when the subscriber responded and was restored to the relay E-4 and consequently to the operator when the subscriber replaced the receiver and deenergized relay F4. 7

When the operator desires to break down the connection after the called subscriber has replaced his receiver, she removes the plug TT from the toll switching jack TSJ. This releases relay O4 Fig. 4 which causes the restoration of all the switches. If, how- The control of the called subscriber still has his receiver v off the switch hook. the switches are not released since relay O4 which controls the release is maintained energized over the following circuit: battery,'left-hand winding of relay O-4, conductor 400, resistance 401, inner left armature of relay F- l, conductor 409, right winding of relay l to ground .at the lower normal contact of switch Y-i, it being noted that the relay F- which controls this loop circuit is itself controlled by relay G& in circuit with the called line and controlled at the switch hook of said line.

Assuming, however, that the called subscriber has replaced his receiver, when the operator removes the plug, relay Olin releasing deenergizes relay Q-d. Relay Q}l in retracting its inner left armature removes ground from the sleeve conductor 410 leading over the sleeve conductor 380. The removal of this ground releases relay D-3 whereupon the release magnet 340 operates as follows: free pole of battery, magnet 340, off normal switch contact 3&1, right armatures and back contacts of relays B3 and A3 to ground at the armature 311 and back contact of relay D3. Thus the incoming selector is restored and upon reaching its normal position opens the off normal springs 313 and 341. The removal of ground from conductors 4:03, by the retrae tion of outer left-hand armature of relay Q- releases relay M4l and the retraction of the right-hand armatures of relay O-4 and right armature of relay Q -d closes the circuit of the release magnet VV-l of the toll transmission selector as follows: free pole of battery, magnet VV4:, lower contactof off normal switch e16, conductor 454, back contact and right hand armature of relay Q-4l to ground at the right-hand armature and back contact of relay O l.

The relay L-4l is provided to permit the toll operator to apply ringing current to a selected private branch exchange line to signal the operator thereat. This relay is operated when relay E-A is'operated due to the actuation of the ringing key by the toll operator. In private branch exchange working the called subscriber may hang up his receiver, but due to the bridge at the private branch exchange operators board the relay G4l remains operated and thus no disconnect signal is given to the toll operator.

What is claimed is:

1. In a machine switching system wherein the toll operator sets automatic switches at a distant automatic office over a two-wire interoffice toll trunk and trunks local to the automatic office, and the completed connection includes a repeating coil at the automatic office, the combination with coin boxes at the substations of the lines having coin disposal magnets therein, sources of collect and refund current at the automatic office, electromagnetic means at said automatic of fice to apply curent from one or the other of said sources to selectively operate said magnet to collect or refund coins, and ll'lQZlilS under the control of the toll operator to con trol said electromagnetic means over said interofiice trunk and local trunks.

2. In a machine switching system wherein the toll operator sets automatic switches at a distant automatic office over a two-wire interofiice toll trunk and trunks local to the automatic office, and the completed connection includes a repeating coil at the automatic office, the combination with coin boxes at the substations of the lines having coin disposal magnets therein, sources of collect and refund current at the automatic office, electromagnetic means at said automatic office to apply current from one or the other of said sources to operate said magnet to collect or refund coins, and means actuated by the coin current applying means for trgnsmitting a characteristic tone back to the toll operator, and means under the control of the toll operator to control said electromagnetic means over said interoflice trunk and local trunks.

3. In a machine switching telephone sys tem wherein the toll operator sets automatic switches at a distant automatic office over a two-wire interoffice toll trunk and trunks local to the automatic office, and the completed connection includes a repeating coil at the automatic office, the combination of coin boxes at the substations of the lines having coin disposal magnets therein, sources of collect and refund current at the auto matic office, a pair of relays at said automatic ofiice, and manual means controlled by the toll operator for operating either of said relays over said interoffice trunks and local trunks to apply current from one or the other of. said sources to selectively operate said magnet to collect or refund coins.

4. In a machine switching telephone system wherein the toll operator sets automatic switches at a distant automatic office over a two-wire interoflice toll trunk and trunks local to the automatic office, and the completed connection includes a repeating coil at the automatic office, the combination with coin boxes at the substations of the lines having coin disposal magnets therein, sources of collect and refund current at the automatic office, and means including a pair of relays at said automatic office, one connected in each side of the trunk, a pair of keys controlled by the toll operator for applying current to either side of the completed connection including said interoffice trunk and local trunks to operate the corresponding relay to supply current from the corresponding source to the said magnet to selectively operate the same.

5. In a machine switching telephone system wherein the toll operator sets automatic switches at a distant automatic office over a two-Wire interoflice toll trunk and trunks local to the automatic office, and the completed connection includes a repeating coil at the automatic o'liice, the combination of coin boxes at the substations of the lines having coin disposal magnets therein, sources of collect and refund current at the automatic office, a pair of relays at said automatic office, and manual means controlled by the toll operator for operating either of said relays over said interoflice trunks and local trunks to apply current from one or the other of said sources, toselectively operate said magnet to collect or refund coins, and means including a source of current controlled by each relay for transmitting a distinctive tone back to the toll operator.

6. In a machine switching telephone system wherein the toll operator sets automatic switches at a distant automatic office over a tWo-Wire interoffice toll trunk and trunks local to the automatic office, and the completed connection includes a repeating coil at the automatic office, the combination of coin boxes at the substations of the lines having coin disposal magnets therein, sources of collect and refund current at the automatic office, a pair of relays at said antomatic oflice, manual means controlled by the toll operator for operating either of said relays over said interofiice trunks andlocal trunks to apply current from one or the other of said sources to selectively operate said magnet to collect or refund coins, a relay in circuit with the said current, and means including a circuit controlled jointly by said relay and the operated coin current applying relay for transmitting a distinctive tone back to the toll operator.

In Witness whereof, I hereunto subscribe my name this 24th day of February A. 1).,

RAY L. STOKELY. 

